Barrier gates that incorporate the use of a pivoting barrier arm are in widespread use. Typical uses of such devices include high occupancy freeway lane entrances, controlled parking lot entries and exits, toll booth lanes, airport entries and exits, railroad crossings, and drawbridges. Most often designs include some sort of actuator to initiate movement of the barrier arm such as a remote control, weight sensitive sensor, or an electronic card reader. Once a signal is received, a motor drives the internal mechanisms to rotate the barrier arm into the open or closed position. The motor and the transmission that convert the rotational motion into the proper orientation and speed are intricate components of the barrier gate system and are costly to repair or replace. Additionally the down time associated with the repair of a damaged motor or transmission prevents the use of the particular lane or passageway causing added expense and possibly traffic congestion. A motor or transmission can be easily damaged if a force from an unexpected direction occurs, moving the barrier. Such a force generally causes the internal gears and linkages of the motor and transmission to be damaged.
Prior art barrier gates have addressed this need in various ways. One way is to design the barrier arm itself to be of a breakaway nature. If an unexpected force is applied to the barrier arm, the barrier arm itself is designed to fail before the components are damaged. While this solution does indeed protect the internal components, the barrier arm itself requires replacement often and the barrier gate ceases to function as a traffic controlling passageway while the barrier arm is missing.
Other prior art barrier gates have designed the internal gears and mechanisms to withstand great pressure before failing by reinforcing them with high strength materials. Typical weather forces or the unwanted manual manipulation of the barrier arm will not be sufficient to move the barrier arm. A design such as this is costly and not marketable but in only the most heavy duty of applications.
Other traffic control devices known in the art such as U.S. Pat. No. 4,101,235 to Nelson employ an elongate series of tire engaging spikes extending transverse to an entering or exit lane of a parking lot or other controlled area. The spikes are carried by a shaft rotatably supported below the surface of the lane. The device discloses a drive means including a reversible electric motor to rotate the shaft between a normal and an actuated position. The device further includes an actuating switch means to cause the motor to rotate the shaft between a normal and an actuated position. Since there is not barrier arm available to lift, the gears of the motor are not in jeopardy from outside forces, but this type of warning lane system can cause expensive damage to the user's vehicle and subject the operator of the system to disgruntled users and possible litigation.
U.S. Pat. No. 4,227,344 to Poppke discloses an automatic parking lot gate with four-way flex connector. The flexible connector includes a first connection plate connected to the arm drive mechanism, a second connection plate connected to the gate arm, and first and second coil springs connected between the first and second connection plates. The coil springs are positioned essentially parallel to one another in a vertical plane. When exposed to outside forces such as a car, the barrier gate will continually flex back towards the starting point and continually apply pressure to the vehicle attempting to gain access. The resilient pressure of the barrier arm can cause damage to the vehicle in the form of dents and abrasions in the paint.